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Date: Thu, 22 Mar 2007 10:12:24 -0700 From: Stephen Hemminger <shemminger@...ux-foundation.org> To: Patrick McHardy <kaber@...sh.net> Cc: Denys <denys@...p.net.lb>, netdev@...r.kernel.org Subject: Re: iproute2-2.6.20-070313 bug ? On Thu, 22 Mar 2007 14:09:06 +0100 Patrick McHardy <kaber@...sh.net> wrote: > Denys wrote: > > /sbin/tc2 qdisc del dev ppp0 root > > /sbin/tc2 qdisc add dev ppp0 root handle 1: prio > > /sbin/tc2 qdisc add dev ppp0 parent 1:1 handle 2: tbf buffer 1024kb latency > > 500ms rate 128kbit peakrate 256kbit minburst 16384 > > /sbin/tc2 filter add dev ppp0 parent 1:0 protocol ip prio 10 u32 match ip dst > > 0.0.0.0/0 flowid 2:1 > > > That is an incredible huge buffer value. > > > qdisc tbf 2: parent 1:1 rate 128000bit burst 4294932937b peakrate > 256000bit minburst 16Kb lat 4.2s > > And it causes an overflow. > > The limit for the TBF burst value with nanosecond resolution is > ~ 4 * rate (10^9 * burst / rate < 2^32 needs to hold), resoluting > in a worst-case latency of 4 seconds. I think this limit is in the > reasonable range. Your configuration results in a worst-case > queuing delay of 64s, and I doubt that you really want that. > > Obviously its not good to break existing configurations, but I > would argue that this configuration is broken. > tc should check for overflows and doesn't. Do you want to make a patch for the obvious cases? -- Stephen Hemminger <shemminger@...ux-foundation.org> - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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